This will be a double-blind, two-arm, cross-over study to assess the safety and efficacy of Dexamethasone in painful sickle cell crisis. Standard supportive measures will continue routinely, including intravenous hydration, narcotin analgesics, and treatment of concommitant infection. We will evaluate the patients' assessment of pain intensity, length of hospitalization, the total analgesic dose, and the interval between discharge from the hospital and the next crisis requiring treatment in the emergency department.